Bottom tracking system
First Claim
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1. A method of bottom tracking, comprising the steps of:
- transmitting a pulse through a medium towards a reflecting surface;
receiving an echo of the pulse from the reflecting surface;
convolving the echo whit the pulse thereby forming one or more convolution peaks on a convolution curve;
processing the convolution peaks with neighboring convolution values so as to form an evaluation curve;
searching for the highest peak on the evaluation curve; and
comparing the highest peak to a threshold value.
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Abstract
A system and method for bottom tracking in a sonar system. The present invention provides for convolving the received signal with the second derivative, or an approximation thereof, of the matched transmitted pulse. In another aspect of the invention, the received signal is convolved with the matching transmitter pulse and the result is evaluated by summing the differences between a central peak and its neighboring left and right values. The filtering of the present invention removes the effect of water absorption on signal amplitude. The invention also includes compensating for spreading loss in the received signal.
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Citations
16 Claims
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1. A method of bottom tracking, comprising the steps of:
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transmitting a pulse through a medium towards a reflecting surface; receiving an echo of the pulse from the reflecting surface; convolving the echo whit the pulse thereby forming one or more convolution peaks on a convolution curve; processing the convolution peaks with neighboring convolution values so as to form an evaluation curve; searching for the highest peak on the evaluation curve; and comparing the highest peak to a threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 14)
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7. A method of bottom tracking, comprising the steps of:
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transmitting a pulse through a medium towards a reflecting surface; receiving an echo of the pulse from the reflecting surface; convolving the echo whit a waveform having the transmit pulse located between pulses which are inverted from the transmit pulse so as to form a convolution curve; searching for the highest peak on the convolution curve; and comparing the highest peak to a threshold value. - View Dependent Claims (8, 9, 10, 11)
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12. A method of bottom tracking, comprising the steps of:
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a transducer oriented to transmit a pulse towards a selected reflecting surface among a plurality of reflecting surfaces and to receive an echo of the pulse; a filter connected to the transducer so as to receive a signal representing the echo from the transducer, the filter having an impulse response that is substantially the second derivative of the transmitted pulse so as to produce a filtered signal; and means for searching the filtered signal for the highest peak among a plurality of peaks, each peak representing a different one of said reflecting surfaces. - View Dependent Claims (13)
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15. A bottom tracking system, comprising:
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a transducer oriented to transmit a pulse through a medium towards a reflecting surface and to receive an echo of the pulse; an amplifier connected to the transducer so as to receive a signal representing the echo from the transducer, wherein a log envelope signal is generated; an envelope sampler connected to the amplifier, wherein the log envelope signal is sampled and then buffered; and a processor connected to the envelope sampler for receiving the signal, the processor including; means for convolving the signal with a matched transmit pulse; means for compensating the convolved signal for the effects of absorption attributed to the medium; means for searching the compensated signal for a highest peak among a plurality of peaks; and means for comparing the highest peak to a predetermined threshold. - View Dependent Claims (16)
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Specification